/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.lucene.index;

import java.io.IOException;

/** Base class for enumerating all but deleted docs.
 * 
 * <p>NOTE: this class is meant only to be used internally
 * by Lucene; it's only public so it can be shared across
 * packages.  This means the API is freely subject to
 * change, and, the class could be removed entirely, in any
 * Lucene release.  Use directly at your own risk! */
public abstract class AbstractAllTermDocs implements TermDocs {

    protected int maxDoc;
    protected int doc = -1;

    protected AbstractAllTermDocs(int maxDoc) {
        this.maxDoc = maxDoc;
    }

    public void seek(Term term) throws IOException {
        if (term == null) {
            doc = -1;
        } else {
            throw new UnsupportedOperationException();
        }
    }

    public void seek(TermEnum termEnum) throws IOException {
        throw new UnsupportedOperationException();
    }

    public int doc() {
        return doc;
    }

    public int freq() {
        return 1;
    }

    public boolean next() throws IOException {
        return skipTo(doc + 1);
    }

    public int read(int[] docs, int[] freqs) throws IOException {
        final int length = docs.length;
        int i = 0;
        while (i < length && doc < maxDoc) {
            if (!isDeleted(doc)) {
                docs[i] = doc;
                freqs[i] = 1;
                ++i;
            }
            doc++;
        }
        return i;
    }

    public boolean skipTo(int target) throws IOException {
        doc = target;
        while (doc < maxDoc) {
            if (!isDeleted(doc)) {
                return true;
            }
            doc++;
        }
        return false;
    }

    public void close() throws IOException {
    }

    public abstract boolean isDeleted(int doc);
}